Many home centers and other retailers of window covering products purchase venetian blinds in stock sizes from a blind manufacturer and display those blinds in retail store locations. These retailers have machines, called cut-down machines, which a salesperson or technician can use to trim a stock blind to fit a window, door or other opening having dimensions smaller than the dimensions of a stock blind. Typically, the customer provides these dimensions. For example, a customer may tell a salesperson that the dimensions of the window to be covered by, the blind are 34 inches wide and 48 inches tall. The stock blind closest to those dimensions is 36 inches wide and 48 inches in length. Consequently, it will be necessary to cut two inches from the width of the stock blind to create a blind that will fit the customer's window. Because the customer usually wants each of the two ladders in a venetian blind of this size to be the same distance from the edge of the blind nearest the ladder, the retailer will cut away an equal amount of material from each edge of the blind rather than cut all the material from one edge of the blind. In the example, one inch would be cut from each edge of the blind. If the blind is too long for the opening, extra slats or other window covering material can be removed from the bottom of the blind. A cut-down machine is not used for this purpose.
There are several types of window covering work piece trimming machines known in the art. One type of machine, disclosed in U.S. Pat. No. 6,615,698 to Chuang et al., has a pair of trimming units, which are adapted from conventional power miter saws. The blind, shade, valance, shutter, headrail, bottom rail, slats, or other window covering work piece to be cut down is placed upon a work surface so that each side of the work piece is fitted through a trimming unit similar to a miter box. An adjustable end stop is provided near each trimming unit to enable the work piece to be positioned in the trimming unit so that the correct amount of material is trimmed from the work piece. The end stops are manually moved by the operator using a rule or scale provided near the end stop. Consequently, an operator of the machine must calculate the amount of material to be removed from each side or end of a stock work piece and then manually position each end stop so that the correct amount of material is cut away.
Another type of blind cutting machine has a cutting mechanism that can cut only one end of a blind. In this type of machine the operator uses the same cutting mechanism to cut one end or side of the blind then repositions the blind and cuts the opposite end of the blind. Most of these machines have a set of cutting dies that act as the cutting mechanism. These machines also have a manually adjustable end stop, which is used to position blind relative to the cutting mechanism so that the proper amount of material is cut away from the blind. The operator of these machines must calculate the amount of material to be trimmed from each side or end of the blind and then use a ruler or scale to position the stop so that the correct amount of material is removed. Examples of this type of machine can be found in U.S. Pat. No. 5,799,557 to Wang and U.S. Pat. Nos. 5,806,394 and 6,196,099 to Marocco.
One major manufacturer provides a mathematical wheel to dial in the width measurements and type of mount. After the variables have been entered the wheel will tell the sales associate the distance at which to set the end stop. Another blind manufacturer provides a modified tape measure on the machine. A piece of plastic is attached to the middle of each blind. That plastic piece is used to align the middle of the blind with a tape measure on the cutting surface.
Whenever an operator must make calculations and set end stops the possibility for errors exists. But, a more significant shortcoming of the blind trimming machines having manually adjustable stops is the time that an operator spends in positioning the end stop. It may take as much as 5 to 10 minutes for a sales associate to complete the entire cutting process. Consequently, there is a need for a blind trimming machine that automatically calculates the amount of material that should be trimmed from a work piece and then automatically positions the end stops, a window covering work piece or both so that the correct amount of material is cut away.